I know, this suggestion sounds strange at the beginning. But if you take a moment to think about it, actually, it makes perfect sense:
1. The best part of goodnotes is not editing text but handwriting strokes. Thus, when text from a keyboard is converted to handwriting strokes, it would be much much easier for majority iPad users.
2. Save a lot of terrible handwriting users, like me. And it also makes notes look more consistent. :-)
3. I guess it would not be too difficult to implement, just let the app pretend to get some perfect user handwriting.